#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2024 Western Digital Corporation.  All Rights Reserved.
#
# FS QA Test No. 747
#
# Inspired by btrfs/273 and generic/015
#
# This test stresses garbage collection in file systems
# by first filling up a scratch mount to a specific usage point with
# files of random size, then doing overwrites in parallel with
# deletes to fragment the backing zones, forcing reclaim.

. ./common/preamble
_begin_fstest auto

_require_scratch

# This test requires specific data space usage, skip if we have compression
# enabled.
_require_no_compress

M=$((1024 * 1024))
min_fsz=$((1 * ${M}))
max_fsz=$((256 * ${M}))
bs=${M}
fill_percent=95
overwrite_percentage=20
testseq=0

_create_file() {
	local file_name=${SCRATCH_MNT}/data_$1
	local file_sz=$2
	local dd_extra=$3

	POSIXLY_CORRECT=yes dd if=/dev/zero of=${file_name} \
		bs=${bs} count=$(( $file_sz / ${bs} )) \
		status=none $dd_extra  2>&1

	if [ $? -ne 0 ]; then
		_fail "Failed writing $file_name"
	fi
}

_total_M() {
	local total=$(stat -f -c '%b' ${SCRATCH_MNT})
	local bs=$(stat -f -c '%S' ${SCRATCH_MNT})
	echo $(( ${total} * ${bs} / ${M}))
}

_used_percent() {
	local available=$(stat -f -c '%a' ${SCRATCH_MNT})
	local total=$(stat -f -c '%b' ${SCRATCH_MNT})
	echo $((100 - (100 * ${available}) / ${total} ))
}

_delete_random_file() {
	local to_delete=$(find ${SCRATCH_MNT} -type f | shuf | head -1)
	rm $to_delete
	_scratch_sync
}

_get_random_fsz() {
	local r=$RANDOM
	echo $(( ${min_fsz} + (${max_fsz} - ${min_fsz}) * (${r} % 100) / 100 ))
}

_direct_fillup () {
	while [ $(_used_percent) -lt $fill_percent ]; do
		local fsz=$(_get_random_fsz)

		_create_file $testseq $fsz "oflag=direct conv=fsync"
		testseq=$((${testseq} + 1))
	done
}

_mixed_write_delete() {
	local dd_extra=$1
	local total_M=$(_total_M)
	local to_write_M=$(( ${overwrite_percentage} * ${total_M} / 100 ))
	local written_M=0

	while [ $written_M -lt $to_write_M ]; do
		if [ $(_used_percent) -lt $fill_percent ]; then
			local fsz=$(_get_random_fsz)

			_create_file $testseq $fsz "$dd_extra"
			written_M=$((${written_M} + ${fsz}/${M}))
			testseq=$((${testseq} + 1))
		else
			_delete_random_file
		fi
	done
}

seed=$RANDOM
RANDOM=$seed
echo "Running test with seed=$seed" >>$seqres.full

_scratch_mkfs_sized $((8 * 1024 * 1024 * 1024)) &>>$seqres.full
_scratch_mount

echo "Starting fillup using direct IO"
_direct_fillup

echo "Starting mixed write/delete test using direct IO"
_mixed_write_delete "oflag=direct"

echo "Starting mixed write/delete test using buffered IO"
_mixed_write_delete ""

echo "Syncing"
_scratch_sync

echo "Done, all good"

# success, all done
status=0
exit
